Paper number 556

HIGH TEMPERATURE STABLE CERAMIC COMPOSITES DERIVED FROM NANO-METALLOPOLYCARBOSILANE AND NANO-METALLOPOLY(BORO)SILAZANE PRECURSORS

Edwin Kroke1, Lutz Ruwisch1, Ralf Riedel1, Brian Derby2, Beverley Inkson2, Alexander M. Tsirlin3, Sergey P. Gubin4, Ella M. Moroz5, Nina A. Popova3 and Elena K. Florina3.

1Fachgebiet Disperse Feststoffe, Fachbereich Materialwissenschaft, Technische Universitšt Darmstadt, Petersenstrasse 23, 64287 Darmstadt, Germany
2Oxford Centre for Advanced Materials and Composites, Oxford University, Parks Road, Oxford OX1 3PH, UK
3State Scientific Center of Russian Federation State Scientific-Research Institute of Chemistry and Technology of Organoelement Compounds, 111123 Moscow, Russia
4Institute of General and Inorganic Chemistry, 31, Leninsky Prospect, 117071 Moscow, Russia
5Boreskov Institute of Catalysis, 5, Prosp. Akademika Lavrentieva, 630090 Novosibirsk, Russia

Summary Polycarbosilanes (PCS) and SiBCN-precursors were chosen for the fabrication of high temperature ceramics in this study. An intermediate polysilane (PS) was synthesized by the Wurtz-reaction and transformed thermally to PCS. In addition molecular compounds with varying Si:B-ratios were prepared by the hydroboration of vinyl silanes. In order to introduce metals into the Si(B)C(N)-polymers appropriate organometallic compounds were selected from compounds of the general formula RnMXq, where R = organic substituent, M = transition metal from group 4 to 7, X = another oxygen-free ligand or CO. Optimized conditions for the synthesis and processing were determined. Intermediate and final products were analyzed by NMR-, UV-, IR-spectroscopy, GC, GC-MS, HPLC, XRD, EXAFS, chemical analysis and TGA-MS. Complete separation of the ligands from the metal atom was found in some cases. The metal compounds decomposed to form nano-particles which are enclosed in the polymeric matrix.
Keywords polymer, ceramic, processing, metal-modified precursors, SiBCN-polymers, nano-particles.

Theme : Ceramic Matrix and C/C Composites ; Processing and Forming

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